Dust Reduction Efficiency Research Articles

Development of New Spray Dust Suppression Materials in Metal Mines and Prediction of Algorithm Simulation Effect

PROBLEM: Dust contamination in metal mining poses substantial dangers to environmental quality and human health. Modern mining operations cannot use traditional spray dust suppression methods because they are poorly adapted to changing climate conditions, low efficient, and detrimental to the environment. INTRODUCTION: Dust pollution seriously impacts the environment and human health in metal mine operations. Traditional spray dust suppression technology has many problems, such as limited effect, environmental impact, and poor climate adaptability. OBJECTIVES: The purpose of this article is to develop a new type of spray dust suppression material and predict its dust suppression effect through algorithm simulation. Firstly, efficient and environmentally friendly dust-reducing materials were screened, and after evaluating the dust-reducing effect under laboratory conditions, the optimal material combination was determined. METHODS: Using computational fluid dynamics (CFD), a numerical model of the spray process was constructed to simulate the dust suppression effect of different materials under different climatic conditions. RESULTS: The results show that the highest dust reduction efficiency of the new spray dust reduction material is more than 4.3% higher than that of the traditional material, and it shows good stability. CONCLUSION: The new spray dust control material and its effect prediction method studied in this article provide an effective solution for dust control in metal mines, which has important theoretical value and practical application prospects.

Recent Patents on Particle Wettability Measurement and Improvement

Background: As the coal mining industry becomes more mechanized, it leads to a large number of coal dust particles suspended in the air, polluting the surrounding environment, accompanied by an increase in fine-grained low-rank coal particles and a low recovery rate of a large amount of organic matter in the particles, wasting resources. Objective: The study of particle wettability can have an impact on spray dust reduction and particle flotation efficiency. By adjusting the hydrophilicity of coal powder particles, the generation of suspended coal dust can be effectively suppressed. By adding surfactants, the flotation separation efficiency of coal particles can be improved. Method: This article introduces the measurement method of particle wetting properties and methods to improve the wetting properties of particles, providing a reference for studying the wetting properties of particles Results: The measurement of particle wetting properties is more accurate, simple, and convenient. Improving the wetting properties of particles by adding additives has significant implications for later dust reduction and particle flotation. Conclusion: This thesis provides an important basis for studying the wettability of particles, modifying the wettability and hydrophilicity of particles, providing specific guidance for improving the wettability of particles for spray dust reduction and particle flotation, and greatly improving industrial production efficiency.

Study on the development and dust suppression performance of a novel composite dust suppressant for metal mines

The significant amount of dust generated during the metal mining process affects both personnel health and the environment. Some mines, such as magnetite mines, produce magnetic dust that is easily adsorbed onto equipment, causing equipment failure and other issues. To solve such problems, a composite dust suppressant was synthesized in this study using carboxymethyl cellulose sodium (CMC-Na), primary alcohol ethoxylate (AEO), and polyethylene glycol (PEG) as raw materials. Firstly, the optimal ratio was determined according to the response surface method. Subsequently, the performance and dust reduction efficiency of the suppressant was evaluated. According to the optimal formulation ratio, the dust suppressant exhibited a viscosity of 34.5 mPa·s and a surface tension of 28.46 mN/m. The wind erosion resistance, compressive strength, and water retention of the dust samples were improved following the dust suppressant application. The loss rates were only 0.025% and 0.9% at wind speeds of 3.5 m/s and 20 m/s, respectively. Simulation experiments indicated that the suppressant achieved a dust suppression efficiency of 82.7% for respirable dust and 90.91% for total dust. These results demonstrate that the suppressant possesses high dust removal efficiency and effective dust suppression, aligning with the application requirements of metal mines and contributing to the mitigation of dust issues during mining operations.

Research on prepositioned air distribution and dust control devices for continuous mining faces

This study, based on the construction of a wind flow-dust two-phase coupled diffusion model, develops a novel method using a prepositioned air distributor to create an air curtain for dust control. This research involved the analysis of wind flow transportation patterns and dust diffusion mechanisms with varying structural parameters, and the verification of simulation results through field tests. The findings indicate that with the increase of the axial horizontal opening angle of the prepositioned air distributor, the wind speed of the air curtain decreases, while the size of the vortex field in the heading face area expands. Increasing the axial vertical opening angle enhances the strength of the vortex, leading to improved dust control abilities. The dust concentration at the rear of the tunnel initially decreases and then rises. Additionally, as the turning angle increases, the speed at which the wind flow diffuses towards the rear of the tunnel also rises. Compared with traditional ventilation methods, the dust reduction efficiency at the respiratory zone height is improved to over 94.0 %. The concentration of dust within the tunnel is significantly reduced, with approximately 98.9 % of the dust confined within a 10.0 m range from the heading face.

Study on dynamic characteristics of anionic surfactants containing ethoxy groups wetting bituminous coal

Coal dust restricts coal mine safety and green production. Wet dust removal is widely used in coal mining, processing and transportation. High-efficiency dust suppressants help control coal dust and improve the working environment. The wetting behaviors of dust suppression droplets on coal affect the dust reduction efficiency. In order to select high-quality and efficient water-based materials, four ethoxy-containing surfactants with similar structures, fatty alcohol ether sulfate (AES), lauryl alcohol sulfosuccinate disodium (MES), fatty acid methyl ester ethoxylates (FMEE) and fatty acid methyl esters ethoxylate sodium sulfonate (FMES), are selected to prepare solutions with different concentrations. Through the droplet impact wetting experimental system, the dimensionless spreading coefficient of droplets is compared. The results show that the spreading behavior of the four surfactant-containing droplets is better than that of distilled water droplets, and the maximum dimensionless spreading coefficient follows the rule of AES > MES > FMES > FMEE >distilled water. The maximum dimensionless spreading coefficient of the droplet first increases sharply with the increase of the concentration, and then increases slowly when the concentration reaches the critical micelle concentration (CMC). The adsorption configuration of water-surfactant-coal system is simulated by molecular dynamics (MD) simulation. The relative concentration distribution of each component and the mean square displacement (MSD) of water molecules are analyzed. The interaction energy of the system is calculated. The simulation results verified the effectiveness of the impact wetting experiment results.

Full-scale study on the coupling settling behavior of droplets and PM10 particles based on the CLSVOF method and wetting experiments

Coal mines produce large quantities of dust during production and transportation of coal, especially respirable particulate matter of diameter < 10 µm (PM10). This not only jeopardizes the health of workers but also pollutes the environment. Currently, spraying is the most commonly used dust reduction technology. Traditional spraying techniques use pure water; however, the wetting and condensing of dust by pure water droplets is poor, resulting in low dust reduction efficiency. To address this issue, we used orthogonal tests to determine the optimal ratio of composite dust-reducing agents. Using the coupled level set and volume of fluid (CLSVOF) method, we investigated the dynamic wetting process of PM10 when using solutions of dust-reducing agents. We found that a particle size ratio of ≥ 2 and an initial velocity of droplets of 20–40 m/s resulted in optimal wetting and encapsulation of dust particles by droplets. We then conducted macroscopic experiments and found that the settling efficiency of PM10 reached 88.98 % when using a 1.5-mm caliber fine atomizing nozzle and a spray pressure of 6 MPa. Our findings reveal the dynamic wetting law of droplets and dust during the process of spray dust reduction, which could lead to improved efficiency of dust-reducing agents and better management of respirable dust. These findings will help to improve clean production in coal mines and the occupational health of coal miners.

Experimental and numerical evaluation of the dust suppression efficiency of an innovative vortex pneumatic fog screen dust control device

To effectively control the dust generated by coal mining operations, a new type of cyclonic pneumatic mist curtain dust control device was developed. Using CFD software, numerical simulations were conducted on the internal airflow velocity field, the exit velocity of the cyclonic pneumatic mist curtain, and the mist droplet particle field of the curtain. Experiments were carried out to measure the spray coverage, droplet size, and the dust control performance of the model device. The results indicate that when the water pump supply pressure is 8 MPa, the fan supply wind speed is 12 m/s, and the nozzle installation angle is 75 degrees, the cyclonic pneumatic mist curtain dust control device model operates under optimal conditions. The effective coverage of the cyclonic mist curtain is 380 × 3300 mm, fully suppressing dust generation on one side of the curtain. An optimal dust removal distance of about 90 cm was determined. After installing the cyclonic pneumatic mist curtain dust control device, the average dust reduction efficiency for respirable dust reached 91.07%, and the overall dust reduction efficiency achieved 93.34%.

Optimization of wind-and-water coordinated dust reduction device for coal mine return airway based on CFD technology

High-concentration respirable dust is generated in fully mechanized mining faces, causing health hazards to operators in return airways. To effectively solve this problem, we developed a wind-and-water coordinated dust reduction device. Firstly, the effectiveness of the numerical simulation was validated through spray experiments. Next, the orthogonal experiment method was employed using software such as Fluent and CFD-Post to conduct numerical simulations. This enabled the analysis of the influence of the fan airflow rate (Q), spray pressure (Pw), and nozzle diameter (D) on the coverage capability of the return air roadway and the distribution pattern of the mist field. The results of the numerical simulations indicated that the optimal combination of parameters was Q = 500 m3/min, D = 1.6 mm, and Pw = 5 MPa. Through field application and actual measurement in the return air tunnel of 117 fully mechanized mining face of Jinjitan Coal Mine, the average dust reduction efficiency reaches 91.05%. After dust reduction, the respiratory dust concentrations in the return airway at 20 m, 50 m and 80 m from the air inlet of the return airway are 0.214 mg/m3, 0.172 mg/m3 and 0.153 mg/m3 respectively, which effectively solves the problem of dust pollution in the return airway and reduces dust harm.

A Numerical Study on Dust Control: Evaluating the Impact of Spray Angle and Airflow Speed in the Coalescence of Droplets and Dust

Spray dust reduction is one of the most economical and effective technologies for controlling coal dust in coal mining faces. We aimed to reproduce a spray dust reduction process in a simulation and investigate the mechanism by which the spray angle and airflow speed influence the dust reduction effect. Based on the DPM (discrete phase model) and the mixture model, we constructed a spray dust reduction evaluation model by considering two-way momentum coupling between the discrete phase and the continuous phase. The results showed that installing nozzles near the dust source (coal mining drum) significantly reduced the dust concentration at the coal mining face from 0.0005 kg/m3 to 0.0001 kg/m3. The increase in airflow speed and spray angle enhanced the horizontal transportation of droplets and dust, providing opportunities for the droplets to condense the dust; however, if the droplets have too large an angle, this will result in an insufficient concentration of droplets in the vicinity of the dust source. When the spray angle is 45°, increasing the airflow speed provides a better dust reduction effect. The nozzle position should also be set scientifically according to the airflow speed. Based on simulation results, a mathematical calculation model of spray dust reduction efficiency was constructed. These results can guide the key parameters of spray dust reduction systems, such as the installation position of the nozzle, the spray angle, and the airflow speed. This paper provides ideas for simulating spray dust reduction for other dust types.

Research of wet string grid dust removal vehicle and creation of dust control area on tunnel working face

The spread of blast dust throughout the tunnel becomes a common problem in drill and blast tunneling,the key to breaking through the problem is the creation of a dust control area on the working face.In view of this key problem, a wet string grid dust removal crawler vehicle was developed, the power of the vehicle came from the diesel generator, and further, the air cooler of the diesel generator was used to generate airflow, and the suction process formed by the on-board axial flow fan was coupled to create a dust control area of the working face after blasting.The results show that when the frequency of the axial flow fan is adjusted to 30 Hz, the airflow speed of the wet chord grid section reaches 3.34 m/s, and the dust removal efficiency is the highest, with a value of 94.3%.Compared with the non-use of the dust removal vehicle, when the air outlet of the air cooler is front, horizontal front, horizontal rear, the dust concentration is reduced by 74.37, 92.39 and 50.53%.Finally, the optimized wet grid dust removal crawler was installed in the Dading tunnel, and the actual dust reduction efficiency was about 78.49%. The results obtained provide an important technical way to improve the working environment of the drilling and blasting construction tunnel.

Investigation of the impact of sodium dodecylbenzene sulfonate modification on the wettability of coking coal

ABSTRACT To investigate the impact of sodium dodecylbenzene sulfonate (SDBS) modification on coking coal’s wettability, our research focuses on coking coal and uses SDBS as the surfactant in the experiment. The surface tension, scanning electron microscope, FTIR, contact angle measurement, and reverse osmosis experiment are employed to measure the microscopic characteristics and wettability of raw coking coal, water-soaked coal, and coal soaked in 0.0005%, 0.005%, and 0.05% SDBS solutions. Finally, the dust reduction efficiency was determined by spray dust reduction experiments. We analyzed the effect of varying mass fractions of SDBS on coking coal’s wettability. The findings indicate that the surface of coal samples soaked in water and SDBS solution become rough. Adding clean water and SDBS solution improves the coal samples’ wettability. Among various coal samples soaked in different solutions, the one treated with 0.005% SDBS solution exhibits the smallest contact angle, significantly higher moisture absorption, and the most pronounced wetting effect. Soaking the coal samples in 0.005% SDBS solution can achieve the highest dust reduction efficiency. In summary, soaking the coal samples in no matter clean water or SDBS solution can enhance the wettability of coal dust, while soaking in 0.005% SDBS solution has a better effect.

Research on factors affecting the spread of dust pollution in conveyor belt workshop and research on wet dust reduction technology.

At this stage, there are many dust-hazardous industries, and occupational pneumoconiosis has a high incidence for a long time. To solve the dust pollution problem in coal processing plant workshops, the dust particle field and liquid droplet particle field were numerically simulated using computational fluid dynamics (CFD), and the influences of the induced airflow and corridor wind speed on the internal airflow field of the workshop were investigated to derive the dust pollution mechanism in the coal plant workshop under the change in the wind flow field. In this study, it was shown that the wind flow rate in the coal processing plant workshop is mainly affected by the corridor wind speed, and the higher the corridor wind speed is, the higher the wind flow rate. The induced airflow mainly affected the direction of the wind flow field in the workshop. According to the conclusions obtained from the simulations, a spray dust reduction system was designed for the coal processing plant workshop and applied in the Huangyuchuan coal processing plant. On-site measurement revealed that the dust reduction effect inside the coal processing plant workshop is obvious, and the overall dust reduction efficiency in the workshop reaches more than 94%, which meets the requirements of environmentally sustainable development and clean production.

Molecular simulation study of the influence of different surfactants on the wetting characteristics of anthracite

The reduction of dust pollution in coal mines is of great importance both for protection of the environment and for the occupational safety and health of coal mine workers. The reduction of dust from anthracite has been a challenge due to its inherent hydrophobicity and high metamorphism. As a result, surfactants are commonly added to water to improve the wettability of coal, thereby improving the dust reduction efficiency of a water spray system. To clarify from a microscopic perspective the effect of different surfactants on the wettability of anthracite, models for the anthracite-surfactant-water system were established, and adsorption configuration, relative concentration distribution, and the diffusion coefficients of water molecules in the systems were thoroughly investigated with molecular simulations. The results showed the directional arrangement of surfactants in the simulation systems after 150 ps of equilibration, resulting in the reduced surface tension of the water-surfactant solution and enhanced wettability of anthracite. Along the (001) normal direction, the relative concentration of sodium dodecylbenzenesulfonate (SDBS) (15.32), the anthracite-water overlapping area, the diffusion rate of water molecules, and the activity (DSDBS = 0.97 × 10-8 m2·s−1) were maximized, indicating the excellent wettability effect of SDBS. The results of the study are of practical significance for improving the wetting effect of anthracite, improving the dust reduction efficiency, and safeguarding the occupational safety and health of personnel.

Experimental study on the charge characteristics and dust reduction performance of inductive electrostatic dual-fluid nozzle for dust pollution control

Dust caused by production activities is the main reason for endangering the production safety and workers' health. To investigate the potential ability of electrostatic dual-fluid nozzles for efficient control of dust pollution, an inductive electrostatic dual-fluid nozzle using profiled electrodes has been designed. From the charge experimental results, the critical voltage of the nozzle is determined to be 12 kV. The maximum droplet charge to mass ratio is achieved when brass electrodes are used. Droplet size and dust reduction experiments show that electrostatic forces enhance the secondary atomization effect and achieve the best parameters at 0.3 MPa water pressure and 0.6 MPa air pressure compared to uncharged dual fluid spray. This nozzle offers a significant improvement in dust reduction efficiency, it can reach more than 78%, an improvement of 18.2% over the uncharged spray. The research results can provide theoretical support for the applications in dust control of inductive electrostatic dual-fluid nozzles.

Experimental study on the synergistic dust reduction of MNBs and surfactants

Spray dust suppression is a primary technological method for controlling coal mine dust. To enhance the wetting and adhesion of droplets to dust particles and improve the efficiency of spray dust suppression, a method of synergistic dust reduction by micro-nano bubbles (MNBs) and surfactants is proposed. This research focuses on MNBs, three different types of surfactants, and low-wetting anthracite coal. Experimental analysis is conducted to investigate the interaction between surfactants and MNBs in solution. The wetting capability of dust particles by the mixed solution of MNBs and surfactants is studied. Additionally, a spray dust suppression experimental platform is employed to compare the dust reduction efficiency of different types of surfactants in synergy with MNBs. The experimental results indicate that surfactants facilitate the generation of nanoscale bubbles, reduce the average diameter of MNBs, and the charge carried by surfactant molecules affects the potential of MNBs. Anionic surfactants decrease the bubble potential, while cationic surfactants elevate it, with non-ionic surfactants having a minimal impact on bubble potential. The presence of MNBs can temporarily reduce the surface tension of a surfactant solution, bringing it to the surface tension at the critical micelle concentration (CMC) but cannot surpass the surface tension beyond the CMC. The addition of low-concentration surfactant solutions to bubbles decreases the contact angle between dust particles and coal dust, while high-concentration surfactant solutions have the opposite effect. In general, the combined use of MNBs and surfactants is beneficial for improving spray dust suppression efficiency. However, extremely high surfactant concentrations lead to an excessive absolute value of bubble potential, enhancing the stability between dust particles and reducing dust suppression efficiency.

Research and Industrial Test of Anti-Freezing and Dust Suppression Agent for Truck Roads in Open-Pit Mines in Inner Mongolia, China

To effectively resolve the inherent conflict between dust control and ice prevention on truck roads during North Surface Coal Mine winters, initially, via monomer preference experiments, the optimal monomers for wetting, moisturizing, and condensing functions were identified as sodium dodecylbenzene sulfonate (B), glycerol (N), and polyacrylamide (R). In parallel, through compound synergistic experiments, the constituent elements of an anti-freezing agent were determined, referred to as F. Subsequently, a four-factor three-level orthogonal test was conducted employing the monomers B, N, R, and the anti-freezing agent F. This evaluation focused on four principal control parameters: penetration rate, evaporation resistance, viscosity, and freezing point. The results led to the identification of the optimal antifreeze and dust suppressant formulation, designated as B2N3R1F3. Within the North Open-Pit Coal Mine, the self-developed dust suppressant was applied to the field test section. Multiple parameters were examined for 6 consecutive days, encompassing the water content of the pavement geotechnical soil, the concentrations of total dust and exhaled dust, and the particle size distribution of dust within this road section. The field test results show that: the average water content of the road surface within the dust suppressant test section measured at 12%; the dust reduction efficiency of total dust and exhaled dust is 93% and 91%; the proportion of dust particles with a size exceeding 500 μm increased by 54.6%. These comprehensive findings provide a empirical framework for the effective resolution of the practical challenge of simultaneously managing dust control and frost protection on truck roads within surface coal mines.

Research on a new method of “blocking-sealing” dust control and removal in fully mechanized heading face

The fully mechanized heading face has the disadvantages of a large open space, difficult to seal, and low dust reduction efficiency. To overcome these issues, a new “blocking-sealing” method for cutting the produced dust was proposed in this study. The impact mechanism of ventilation parameters on dust pollution was analyzed using the CFD-DPM method. The results show that in the original state, the transverse offset airflow generated by the roller of the heading machine carries high-concentration dust into the sidewalk space, the length of the high-concentration dust area of more than 570 mg/m3 in the sidewalk space is about 16 m. After using the new method, the distribution of airflow mechanical energy between the sidewalk space and the bracket-coal wall space was redistributed. When the air suction volume was 600 m3/min, the high-concentration dust area basically disappeared. By increasing the air volume ratio to 1:1.5, the dust concentration in the original high-concentration dust area of the sidewalk space was basically lower than 172 mg/m3. When the side opening of the dust exhaust duct for suction (SO), the dust removal efficiency in the local area of the sidewalk reached 80.7%, which provides a new method for clean coal production.

Assessment of Water Retention Capacity of Non-Ionic and Anionic Fluorinated Dust Suppressants on Coal Dust

Wet-spray dust reduction technology is one of the many dust control measures used to address the underground coal dust hazard. The wettability and agglomeration effects between coal dust and dust suppression solution directly affect the dust reduction efficiency. The water retention of the dust suppression solution also affects the wetting effect of coal dust and the possibility of secondary dust generation after settling.. Fluorinated solutions are known for their good thermal and chemical stability and ability to reduce interfacial tension with a small dose, while also maintaining surface activity in the solution system. This study investigated the wetting and agglomeration effects of non-ionic and anionic fluorine-containing solutions at different concentrations in conjunction with coal dust by studying the water retention of coal samples. The experimental results show that the water retention of the non-ionic fluorinated solution is significantly better than that of the anionic fluorinated solution. The lowest mass loss was 10.0909 g for FS-31 and FS-34 at 0.03% concentration. The best overall solidification state of the coal sample surface after the experiment was attained with the FS-50 solution. The surface of the coal sample was dense and crack-free, with the lowest probability of secondary dust emission.

Study on the influence pattern and efficiency enhanced mechanism of acoustic–chemical spray dust reduction

To study the influence pattern and efficiency enhanced mechanism of acoustic–chemical spray method on dust reduction, a self-developed acoustic excitation test platform, viscosity test, surface tension experiment and sinking experiments were used to investigate the chemical spray properties and the wetting behavior of coal dust excited by acoustic waves. The self-developed acoustic–chemical spray dust reduction simulation platform was used to study the influence of acoustic waves on coal dust reduction effect and its efficiency enhanced mechanism. The results showed that the surface tension and viscosity of the chemical spray solution fluctuated between 0.4 mN/m and 0.4 mPa·s along with the variations in acoustic wave frequency and sound pressure level (SPL), thereby confirming that acoustic waves had on effected on chemical spray solution properties. However, the wetting time of the chemical spray solution on coal dust increased by 33.64 % at an acoustic frequency (f) of 1300 Hz and SPL of 120 dB because of the liquid interface vibrations caused by acoustic waves. With an increasing of acoustic frequency, the dust reduction efficiency demonstrated a parabolic trend and reached its maximum value at f = 1300 Hz. The dust reduction efficiency also increased exponentially along with increasing SPL. Acoustic waves not only increased the collision frequency between particles and droplets by changing the trajectory of dust but also accelerated the wetting and agglomeration effect of chemical spray reagents on coal dust by causing vibrations at the gas–liquid interface, thereby enhancing the dust reduction efficiency. Compared to the dust reduction efficiency of chemical spray technology, the total dust reduction efficiency was increased by 8.53 %, and the respirable dust reduction efficiency was increased by 21.93 %. The effect of acoustic waves on the respirable dust reduction efficiency was more significant than that on total dust.

CFD Simulation Based Ventilation and Dust Reduction Strategy for Large Scale Enclosed Spaces in Open Pit Coal Mines—A Case of Coal Shed

The coal shed is an enclosed space where raw coal is stored and handled. The intensive operation of the machinery inside the coal shed generates a large amount of dust, and the wind speed inside the enclosed space easily leads to a high concentration of dust, which endangers the physical and mental health of the workers. In this paper, we first studied the particle size distribution of dust samples in the coal shed and found that 12.2% of the dust in the air of the coal shed was 10–100 μm, 87.8% was less than 10 μm, and 72.9% was less than 2.5 μm. Fluent was used to simulate the law of dust dispersion in the coal shed under different working conditions, and finally, the simulation results were used to guide the design of the ventilation site and dust-reduction scenario. The experimental and simulation results show that under the same working conditions, the average dust reduction efficiency of the ventilation method in which the north side and south side pump air outside was 9.9%. The ventilation method in which the north side blows inside and the south side pumps outside was 23.7%. The average dust reduction efficiency of the ventilation method in which the north side blows inside and the south side pumps outside + placing the fan in the middle was 59.9%. The research results can provide some reference value for indoor air quality improvement.